Hi folks,
I have a parser problem. I have a basic calculator program (Graham Hutton's from Nottingham) which contains the following code:
-- Define a parser to handle the input
expr :: Parser Int
expr = do t <- term
do symbol "+"
e <- expr
return (t + e)
+++ return t
term :: Parser Int
term = do f <- factor
do symbol "*"
e <- expr
return (f * t)
+++ return f
factor :: Parser Int
factor = do symbol "("
e <- expr
symbol ")"
return e
+++ natural
symbol and natural are defined elsewhere and work fine, but when I compile it I get the error
ERROR "C:/HUGS/Calculator.hs":66 - Undefined variable "t"
I suspect I'm missing something obvious, but for the life of me I can't see it. Any suggestions?
Thanks,
Nik
(Trying to keep a couple of weeks ahead of her students)
Dr Nik Freydís Whitehead
University of Akureyri, Iceland
*********************************************************************
Having the moral high ground is good.
Having the moral high ground and an FGMP-15 is better.
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